Frequently expensive gas turbine engine components, like turbine blades and vanes, experience burn-through, diffusion-controlled deformation (“creep”), cyclic loading and unloading (“fatigue”), chemical attack by hot gas flow (“oxidation”), wear from rubbing contact between blade tips and turbine shrouds, wear from the impact of particles entrained in the gas flow (“erosion”), foreign object damage (“FOD”), and the like, throughout their extended service. Although such damage to the exterior of the component may be relatively small, the damage experienced by the internal geometry designed to direct a cooling airflow within the component may be more severe. In fact, the damage may be severe enough to affect or damage the internal configuration of the component. Defects of this nature are often sufficient to cause rejection of the component. In certain instances, the defect is of such a nature that repairs would be satisfactory. However, lacking a suitable means for reliably repairing such defects, these blades and vanes are often scrapped.
Current welding techniques may introduce additional problems beyond the existing damage. For instance, the weld material may flow into the exposed internal geometry and result in a rejectable condition. In other areas, such as a trailing edge, weld repair may result in the closure of the internal geometry, such as internal cooling features, that may then need to be re-established by labor intensive blending or electrodischarge machining.
Consequently, there exists a need for a satisfactory repair technique for restoring both the external features and internal geometry of damaged parts.
There also exists a need for a satisfactory repair technique for restoring the internal geometry of a part in accordance with the original design specifications.
There also further exists a need for a satisfactory repair technique for restoring the internal geometry of a part and maintaining the symmetry of the internal core.